The present invention relates, in general, to the production of fiber products, and particularly dietary fiber products, from various fiber-containing plant material such as fruits, grains, vegetables and cellulose products. More specifically, the present invention relates to a process, and resulting product, and the apparatus for the production thereof, which is capable of producing a dietary fiber of high water-binding capacity, that in turn may be used to produce high fiber food products.
Diets high in fiber have been endorsed by many sources for the potential health benefits they offer. High fiber diets are reported to reduce the risk of colon and rectal cancers and to reduce blood serum cholesterol levels. In addition, since fibers are not easily digested by humans, dietary fiber ingredients are non-caloric and contribute to a reduction in total food calories consumed when used as a replacement for carbohydrates, proteins, and fats in a wide variety of food product formulations.
The total dietary fiber (TDF) of a food or food ingredient is in two forms: soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). Soluble dietary fiber can be defined as a fiber that is soluble in aqueous solutions designed to simulate human digestive systems. However, the term soluble fiber often is used loosely to refer to the solubility of the fiber in water. If a fiber is declared water-soluble this does not mean a completely dissolved state, as for example, glucose would be in water. Solubility of fiber is the dispersion state of the polymer in water, existing in a colloidal dispersion. Insoluble dietary fibers resist even a colloidal dispersion.
Many dietary fibers are marketed for use in formulating xe2x80x9chealthyxe2x80x9d food products. Typical fibers and their TDF, SDF, and IDF are shown in Table I below.
In the baking industry, for example, formulating healthy or high-fiber food products is greatly affected by the ability of the dietary fiber to absorb or bind water. The ability to fix water in baking formulations contributes a pleasing moistness, adds fullness, and improves the appearance of many baked food products. However, serious functional problems are frequently encountered when formulating foods containing high-fiber ingredients. Flavor and color are inherently critical to bread and cereal products intended for consumer use. Bakers, therefore, face tradeoff decisions when adding dietary fiber to baked products. Using too much fiber can produce unwanted flavors, colors, and textures.
The ability of a fiber to bind water creates a moister food product. Most fibers available to the baking industry can absorb (bind) two to four times their weight in water. Increasing the water binding capacity of baked goods having dietary fiber added to their formulation often must be achieved by using gums and pectin, rather than the fiber itself.
The water-binding capacity of various dietary fibers is set forth in Table II below.
Texture problems in baked products can include: lack of volume or expansion in baked goods or cereals, non-uniform texture, unpredictable water holding and/or absorption characteristics, interference with the production of extruded and expanded cereals or snacks, and qualitative problems, such as xe2x80x9cmouth feel.xe2x80x9d One approach to controlling unwanted textures is by maintaining fiber size below 100 microns. Fibers with a small size minimize the impact of coarse xe2x80x9cmouth feelxe2x80x9d or visual granularity, which bakers typically wish to avoid.
Various processes have been devised in order to extract dietary fiber from fiber-containing sources. Typical of the patent literature relating to dietary fiber extraction are U.S. Pat. Nos. 5,137,744, directed to a sugar beet fiber extraction process, and 5,350,593, directed to a tapioca pulp fiber production process.
U.S. Pat. No. 5,137,744 achieves fiber extraction primarily based upon heating, and is directed to the reduction of off-odor and off-flavor problems which are encountered with sugar beets. Hydrogen peroxide is used as part of the fiber treatment process. U.S. Pat. No. 5,350,593 employs both enzyme treatment and bleaching of tapioca fiber. The bleaching takes place after the enzyme treatment and numerous bleaching agents were tried, including benzoyl peroxide which produced a poor result.
U.S. Pat. No., 5,403,612 discloses a process for producing a pectin-containing fiber product from fruits, vegetables, grains and grasses. One possible fiber source is listed as carrots. In U.S. Pat. No. 5,403,612, however, the fiber material obtained from the various fiber sources is processed in a manner which results in fiber containing pectin, which thereafter is subject to phosphorylation. U.S. Pat. No. 5,354,851 also discloses a process for manufacturing a crude pectin containing product from various fiber containing fruits, vegetables, including carrots, and grasses using an ion exchange method. The use of ion exchange is also disclosed in U.S. Pat. No. 5,863,582 for the processing of various vegetables, including carrots. Finally, U.S. Pat. No. 4,599,237 discloses the use of various bleaching and maturing agents in a process for augmenting or enhancing the aroma of food stuffs.
It also is known to use carrots as a source for dietary fiber in which the carrots are ground and then dehydrated to produce a fiber supplement. See, e.g., xe2x80x9cDoes Chronic Supplementation of the Diet with Dietary Fibre Extracted from Pea or Carrot Affect Colonic Motility of Man?,xe2x80x9d British Journal of Nutrition, Vol. 76, pp 51-61 (1996). The carrot fiber studied, however, was not a sugar-free, colorless, odorless, tasteless product which would be suitable for fiber fortification of other food products.
Accordingly, while it is known to extract dietary fiber from a wide variety of fiber-containing plants, there is a considerable need for a process which is capable of producing a fiber product, and particularly a dietary fiber product, which has desirable organoleptic properties and has a substantially enhanced water-binding capacity, as compared to conventionally produced dietary fibers.
It is, therefore, an object of the present invention to provide a dietary fiber production process, apparatus and fiber product, which has high water absorption capacity and desirable organoleptic properties, as well as to provide food products made therefrom.
In one aspect, the present invention comprises a process for producing a fiber product having a high water absorption or binding capacity. This process is comprised, briefly, of the steps of selecting carrot material as the source for the fiber product; leaching sugar from a puree of carrot material using an aqueous solution until the sugar remaining in the carrot material has been substantially reduced; after the leaching step, separating the carrot material having a particle size below a predetermined level from the aqueous solution; adding back a new aqueous solution to the carrot material; bleaching the separated carrot material while in the aqueous solution with a bleaching agent; and after the bleaching step, removing the bleached carrot material from the aqueous solution, and drying the bleached carrot material to produce a dried carrot fiber product having a high water absorption capacity.
The water absorption or binding capacity of the resultant fiber product produced by the process of the present invention will typically be in the range of 8 to 15 times the weight of the carrot fiber end product. In the preferred process, the sugars are leached from the puree of carrot material until the sugar is below about 1 weight percent. The puree is wet-ground to pass through a sizing device before bleaching and is bleached at an elevated temperature using an organic peroxide or peracitic acid as a bleaching agent. The aqueous solution is then separated and the bleached carrot material is preferably flash dried at temperatures above 500xc2x0 F., followed by milling and sizing to produce a food grade dietary fiber product having high water-binding capacity.
In another aspect, the apparatus of the present invention is comprised, briefly, of a mixing apparatus, a water removal assembly formed to receive a mixture of a puree of carrot material and aqueous solution and to separate the carrot material from the solution; a source of aqueous solution connected for input into the mixing apparatus; a grinding device receives carrot material from the water removal assembly and formed to grind the carrot material puree, while in an aqueous solution; a sizing device receives the ground puree and is formed to allow passage of carrot material below a predetermined particle size into a mixing reservoir; a source of bleaching agent is coupled for input to the mixing reservoir; a water separation device is positioned to receive the bleached puree and is formed to remove aqueous solution so as to substantially increase the solid contents of the carrot material puree; and a dryer assembly is connected to dry the carrot material preferably by flash drying the material at an extremely high temperature. Optionally the flash dried carrot material is ground in a turbine mill while drying continues and then sized further before use.
In a final aspect, food products made from dietary fiber produced by the process and the apparatus of the present invention are provided.